USE OF SELF-INTERROGATION NEUTRON RESONANCE DENSITOMETRY (SINRD) TO MEASURE THE FISSILE CONTENT IN NUCLEAR FUEL

摘要

We investigated a new method to verify the concentration of fissile material in a PWR fresh fuel assembly using Self-Interrogation Neutron Resonance Densitometry (SINRD). Monte Carlo NParticle eXtended transport code (MCNPX) was used to simulate these measurements. The sensitivity of SINRD is based on using the same fissile materials in the fission chambers as are under investigation because the effect of resonance absorption lines in the transmitted flux are amplified by the corresponding (n,f) reaction peaks in fission chamber. This simulation utilizes the ~238U spontaneous fission neutrons to self-interrogate the fuel pins. The amount of resonance absorption of these neutrons in the fuel can be measured using ~235U fission chambers placed adjacent to the assembly. We used ratios of different fission chambers to reduce the sensitivity of the measurements to extraneous material present in fuel. The development of SINRD to measure the fissile content in spent fuel is of great importance to nuclear safeguards and accountability. Future work includes the use of this technique to measure the concentration of fissile materials in spent fuel and pyroprocessing heavy metal product.